Cable ties and their accessories, such as mounting bases, have been extensively used for several decades. Cable ties are quite useful in bundling wires or in tethering items to each other or to a support structure. Some cable ties are made of metal, some are made of plastic and some consist of a combination of metal and plastic.
The strength of a cable tie and/or its accessory is dependent on the material used to construct the cable tie, as well as the cross-sectional area of the cable tie. For a given material, the greater the cross-sectional area, the greater the strength. Thus, in order to maximize the strength, great effort is taken to eliminate any voids or air pockets which would diminish the cross-sectional area of the cable tie and hence its strength. It is important for the cable tie to maintain a certain minimum cross-sectional area along its length and for the accessory to remain intact and not rupture or break.
As a result of their solid no-void construction, cable ties and their accessories are not buoyant because they are typically made from materials having a specific gravity greater than water. An attempt to overcome this inability to float was made in U.S. Pat. No. 5,690,522 to Moreau, which discloses a floatation device that can be attached to the cable tie to provide buoyancy. However, this solution to the problem adds extensive cost since not only must another component be manufactured, but the user or the manufacturer must also assemble the two together. Additionally, the cable tie is now bulky and it is more difficult for the bundled wires to slide within a bulkhead or cable tray, and it is more difficult for other items to slide along the tied bundle due to the projection of these flotation devices. Also, such a flotation device is attached to only one section of the cable tie. Therefore, the flotation does not work when the cable tie is severed into two or more pieces, or when the cable tie accessory is separated from the cable tie, because only one flotation device is provided.
Cable ties can be made from materials that contain air voids, which would reduce the specific gravity of the cable ties. However, such a design provides an inferior product because the air pockets create areas of weakness along the cable tie. As stated above, the strength of a cable tie comes from a combination of the material of construction and the absence of voids in its cross-sectional area. Thus, if the cable tie material is displaced by air or otherwise contains voids therein, the strength of the cable tie is severely compromised. While it may be possible to construct a cable tie that floats due to air pockets in the materials, its strength would vary greatly because the quantity and the size of the internal air pockets would be randomly dispersed. Consequently, such a tie would easily break if too many air pockets (or if too large an air pocket) occur along any load-bearing cross-sectional area of the tie or device. The inherent weakness of the cable tie could not be detected until the cable tie actually broke. Accordingly, cable ties with voids are not a satisfactory solution for the user.
Many different industries, such as the food, pharmaceutical, rubber molding and nuclear industries, employ different types of detection equipment in order to remove any impurity or stray item that may be found in a product or process stream. Such devices include vision, photo or optic systems; systems that compare the product against an ideal configuration for such product; and X-ray or metal detection devices that use density or magnetic properties for detection. These industries make every effort to detect and remove any foreign material that inadvertently enters any critical product or process stream before any harm is caused.
Cable ties formed from plastic resins, whether they are of one-piece or two-piece construction, are generally identified or referred to in the industry as nylon or plastic cable ties. The density of these cable ties can vary depending on the plastic resin used. Consequently, cable ties, or portions of cable ties, that inadvertently enter a product stream can sink to different depths in the stream, or all the way to the bottom, depending in part on the density of the cable tie materials and the density of the process stream material.
One cable tie manufacturer has added metal particles to nylon cable ties so that they can be detected in the event that a tie breaks or a cut-off tail ends up where it is not wanted. The metal particles allow the cable ties or tails to be more easily detected, located and removed. These ties are sold by Hellermann-Tyton as Model No. MCT50L and described in the advertising literature as metal content ties, which are able to be detected by standard metal detecting equipment. However, in order to assure that the ties can be detected, the Hellermann-Tyton cable ties have a very high metal particle content. Hellernann-Tyton discloses in its literature that the composition used to make the cable ties contains polyamide (nylon) 6,6 and 10% metal particles. This results in a cable tie with a density greater than 1.8 which cannot float in water and almost immediately sinks to the bottom of a process stream.
Thus, it is an object of this invention to provide detectable cable ties and accessories that are buoyant. A further object of this invention it to provide a floating cable tie that contains metal particles and/or compounds without resorting to add-on devices. Still another object of this invention is to provide floating cable ties and accessories without compromising the integrity or affecting the strength of the cable tie. Yet another object of this invention is to provide a buoyant cable tie that is similar in shape and function to cable ties currently in use so that users can readily adapt to the new design. Another object of this invention is to provide a cable tie with ferrous or non-ferrous additives which facilitate the detection of the cable tie and any portion or component thereof. These and other objects and advantages of this invention will become obvious in view of the description below.